You need to use the shortcode, if you like the default option then use the shortcodes for Loginand for Sign Up
Yes the plugin can be used ad widget in sidebar you need to go in Appearance > Widget
This happens when you are already logged in to WordPress. Try to test it in incognito mode of your browser while you are logged out of WordPress./p>
Try to go in WordPress Settings > General > Membership > and select “Anyone can register” check box
Yes you may upgrade the license by only paying the difference.